This invention relates to the implementation of logic or switching functions by non-magnitude based physical phenomena. More specifically it provides novel methods and apparatus to implement a logic state by using a characteristic of a physical phenomenon that is not based on a magnitude or amplitude of a signal.
Binary logic or binary switching is currently mainly provided in electronic circuits. The signals representing the states in binary logic are usually magnitude based. Binary logic or switching of course has 2 states, which are usually called 0 and 1. The two states are usually represented by a magnitude of an electric signal, either as a voltage or as a current. Sometimes a magnitude is a phase of a signal. For storage also the magnitude of a charge is used. For binary logic one of the states, but usually the 0, is represented as ground or absence of signal. A 1 can be represented as for instance 1.5 Volt or 0.5 Volt or whatever voltage is convenient. The representation of a state by a voltage is not really required, but is commonly used. The 0 can be represented by another voltage. Sometimes the opposite voltage of the one selected for 1 is used for 0; for instance −1.5 Volt. However often 0 Volt or ground or absence of signal is selected as representing a 0 state.
It should be clear that in the binary case the magnitude of the electrical signal determines the state it represents. Use of representing a signal with a certain frequency as a state is also known. For instance Frequency Shift Keying (FSK) uses 2 frequencies representing 0s and is in transmission systems.
One also applies Multiple Frequency-Shift Keying (MFSK) in state representation for transmission purposes, representing each of different and more than 2 states by a frequency. The advantage herein is that one has to detect the presence or absence of a signal to determine a state. The use of magnitude based signals, such as voltage based representation has an inherent problem with noise. In detection of an mth voltage level one can be off by for instance one level. Thus one may for instance detect state (m−1) or state (m+1) instead of m. Accordingly when a state is ‘sandwiched’ between two other states, potential errors are more likely.
This aspect is well known in for instance transmission theory. One may address this problem in optimizing the ‘eye’ of the signal and optimizing the moment of the detection of the presence of a signal level.
Applying detecting a presence or an absence of one of n signals appears to be more robust than detecting one of n levels. One actually buys better performance by using more resources for detection and by using more bandwidth.
In general it is more robust to detect a state of a phenomenon by detecting the presence or absence of the phenomenon rather than one of more than several magnitudes of the same phenomenon. In fact one may say that the problem is reduced to a plurality of binary detections. However, while multi-valued logic signals implemented by non-magnitude based physical phenomena are more robust than magnitude based representations, the implementation of logic functions wherein logic states are represented by non-magnitude based phenomena are currently unknown.
Accordingly novel and improved methods and apparatus for implementing binary and multi-valued logic or multi-state switching functions and signals by non-magnitude based physical phenomena are required.